Unlocking the nutritional potential of Australian yam (Dioscorea spp.)

Yam ( Dioscorea spp.), a staple food among Australia's First Nations people, has nutritional, cultural, and historical significance, connecting them to their land, identity, and well-being. However, information on the nutritional value and quality characteristics of the tubers and their main nutritional component (starch) are lacking in literature. This study investigates the nutritional composition of the flesh and peel from two yam species ( D. alata (DaF and DaP) and D. bulbifera (DbF and DbP)), as well as the physicochemical properties of their starch, which can affect their food and non-food uses. The flesh and peel of the tested yam species had a high moisture content (high fresh weight), with starch being the main component in the flesh of both species (DaF-55.8%, DbF-68.9%). The peel and flesh are low in fat and protein, a good source of dietary fibre, with fructose, glucose and sucrose being the main sugars present. The flesh and peel are high in minerals (K, Ca, Na and P), trace (Cu) and ultra-trace elements (Rb, B), as well as essential amino acids. The starch peak gelatinization (Da-78.0 and Db-78.1°C) and pasting temperature (Da-84.0 and Db-84.1°C) in both species were relatively high, with the D. alata peak viscosity (8000cp) significantly (p <0.05) higher than that of D. bulbifera (7701cp). This study affirms First Nations Peoples traditional knowledge of yams’ nutritional value, highlighting their potential for integration into the Australian ‘mainstream’ diet. Promoting indigenous foods is also a successful strategy to develop environmentally friendly and sustainable supply chains.